@article {2690,
	title = {Late glacial and Holocene paleoenvironments in the midcontinent United States, inferred from Geneva Lake leaf wax, ostracode valve, and bulk sediment chemistry},
	journal = {Quaternary Science Reviews},
	volume = {241},
	year = {2020},
	month = {Jan-08-2020},
	pages = {106384},
	abstract = {Geneva Lake in Wisconsin, USA, is > 20,000 years old and contains a 30-m thick lacustrine sediment record of mid-continent North American climate and environmental change. Here we describe a sediment record from Geneva Lake spanning the past 14,500 years. From scanning X-ray fluorescence, organic C and N concentrations and isotopes, X-ray diffraction, magnetic susceptibility, and grain size of bulk sediments, we infer changes in sediment sources over time including: abrupt decline in inputs of remobilized loess \~{}13,400 cal yr BP followed by a gradual transition to organic-rich marl deposition by \~{}10,400 cal yr BP as the landscape stabilized following a period of permafrost thaw and vegetation development; deposition of a minerogenic unit at \~{}8,200 cal yr BP that may record enhanced eolian activity during the widespread {\textquotedblleft}8.2 ka event; {\textquotedblright} and elevated zinc, lead, and arsenic from human activities following regional industrialization. Within the Holocene marl, we also use isotopic (δ18O and δ13C) and trace metal ratio (Sr/Ca and Mg/Ca) analyses of ostracode valves paired with concentrations and hydrogen isotopic composition (δ2H) of leaf wax n-alkanes to infer climate and hydrological change. Groundwater had a large but declining influence on lake water chemistry from 11,800 to 9,700 cal yr BP, precluding inferences of regional climate from our lacustrine proxies during this period. δ2H values of terrestrial n-C29 alkanes show little variability from 9,700 to present, indicating the average isotopic composition of local precipitation was relatively stable, reflecting stable condensation temperatures and source. In contrast, a gradual trend towards more δ18O- and δ2H-depleted lake water and lower lake water Sr/Ca from 9700 cal yr BP to present suggest decreasing evaporation of lake water and increasing precipitation amounts throughout the Holocene and resulting shorter lake water residence times. Lake water Mg/Ca variations over the past 9,700 years broadly parallel regional pollen-based reconstructions of summer temperatures. Neither Mg/Ca nor terrestrial leaf wax δ2H suggest long-term directional shifts in temperature at this site through the middle to late Holocene, as climate became wetter. It appears that precipitation isotopes did not track local temperatures on millennial timescales in this part of mid-continent North America through the Holocene, and instead may have covaried with changes in Northern Hemisphere latitudinal temperature gradients driven by large Arctic temperature changes.},
	keywords = {Holocene, Inorganic geochemistry, Loess, North America, Organic geochemistry, paleoclimatology, paleolimnology, Pleistocene, sedimentology, Stable isotopes},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2020.106384},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379120303462},
	author = {Puleo, Peter J.K. and Axford, Yarrow and McFarlin, Jamie M. and Curry, B. Brandon and Barklage, Mitchell and Osburn, Magdalena R.}
}
@article {2845,
	title = {Stable source of Holocene spring precipitation recorded in leaf wax hydrogen-isotope ratios from two New York lakes},
	journal = {Quaternary Science Reviews},
	volume = {240},
	year = {2020},
	month = {Jan-07-2020},
	pages = {106357},
	abstract = {Changes in synoptic atmospheric circulation patterns are thought to play a role in establishing millennial scale climate periods during the end of the late glacial and the Holocene. In the northeastern United States, multi-proxy evidence documents fluctuations in effective moisture and temperatures for this time period, but constraining the relationship between atmospheric processes and these climate regimes is not straightforward. Because the hydrogen-isotope ratios of sedimentary terrestrial leaf waxes can reflect precipitation δD, these long-chain hydrocarbon compounds are an excellent tool to investigate moisture sourcing. Here we present lake sediment and leaf wax carbon- and hydrogen-isotope records that span the past \~{}14.0 thousand years from Heart Lake and Moose Pond in the Adirondack Mountains (ADK), New York. High initial lake productivity after basin inception is reflected in low C:N ratios (<15), and higher relative short chain n-alkane (n-C17, n-C19, and n-C21) to long chain n-alkane (n-C27, n-C29 and n-C31) concentration ratios. The Holocene record is characterized by low bulk and n-alkane δ13C (\~{} -28{\textperthousand}, \~{} -31{\textperthousand}, respectively), high ACL25-35 (\~{}28), and high relative concentrations of long chain n-alkane homologues, indicating a dominantly terrestrial source of organic matter for this time period. Hydrogen-isotope ratios of n-C29 n-alkane from both lake basins range only \~{}20{\textperthousand} through the Holocene and reconstructed precipitation δD (δDprecip) from both basins is in good agreement with that of modern modeled spring precipitation. This suggests there may have been no major changes in the sourcing of spring precipitation for the ADK throughout the time of record.},
	keywords = {Holocene, Hydrogen isotopes, late glacial, Leaf wax, North America, Organic geochemistry, paleoclimatology, Precipitation sourcing},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2020.106357},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S027737912030319X},
	author = {Schartman, Anna K. and Diefendorf, Aaron F. and Lowell, Thomas V. and Freimuth, Erika J. and Stewart, Alexander K. and Landis, Joshua D. and Bates, Benjamin R.}
}
@article {2691,
	title = {Holocene and Last Interglacial climate of the Faroe Islands from sedimentary plant wax hydrogen and carbon isotopes},
	journal = {Quaternary Science Reviews},
	volume = {223},
	year = {2019},
	month = {Jan-11-2019},
	pages = {105930},
	abstract = {The Last Interglacial period (LIG) is Earth{\textquoteright}s most recent globally warm period and is analogous in some ways to projected future global warming. However, questions remain regarding the state of the climate during the LIG in the North Atlantic, a region that is extremely sensitive to changes in oceanic and atmospheric circulation. Here, we present hydrogen and carbon isotope (δD and δ13C) records from a suite of plant wax biomarkers preserved in Holocene and LIG lacustrine sediments from the North Atlantic Faroe Islands and interpret them as qualitative proxies for temperature and hydroclimate variability. These data are used to directly compare LIG and Holocene climate using the same proxy approaches from the same terrestrial location. Measuring multiple isotopes on multiple types of waxes elucidates the sources of homologous plant waxes. We deduce that the δD values of long-chain n-alkanes (C27{\textendash}C33) and mid-chain n-alkanes (C23{\textendash}C25) in these sedimentary archives reflect leaf water and lake water δD values, respectively, while the δD values for both long-chain (C28{\textendash}C30) and mid-chain n-alkanoic acids (C24{\textendash}C26) primarily represent lake water δD values. Plant wax-inferred δD values of precipitation during the early Holocene (10,100 to 8,200  cal  yr BP) are \~{}35{\textperthousand} more positive than late Holocene values, and decline over the Holocene. δD-inferred hydrologic change and δ13C -inferred plant water use efficiency both indicate that the Faroe Islands became drier throughout the Holocene. Comparison with measurements from LIG plant waxes indicates that late LIG in the Faroe Islands was hydrologically similar to the early-to mid-Holocene (8,200 to 4,000  cal  yr BP), with enriched precipitation isotopes and reduced evapotranspiration indicating a warmer, wetter environment.},
	keywords = {Holocene, interglacial, North Atlantic, Organic geochemistry, paleoclimatology, Stable isotopes},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2019.105930},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379119304251},
	author = {Curtin, Lorelei and D{\textquoteright}Andrea, William J. and Balascio, Nicholas and Pugsley, Genevieve and de Wet, Gregory and Bradley, Raymond}
}
